Suppression of boron penetration through thin gate oxides by nitrogen implantation into the gate electrode

PMOS devices with different amounts of nitrogen incorporated into the gate electrode by implantation were manufactured, Nitrogen implantation into the gate electrode of PMOS devices was applied before BF, implantation and annealing by rapid thermal annealing for doping the gate electrode. The thickness of the gate oxides grown at low pressure in dry oxygen by rapid thermal oxidation were 4.1 down to 2.8 nm. The influence of the nitrogen implant on the penetration of boron ions through the ultra-thin gate oxides into the channel region was investigated by electrical and SIMS measurements. Boron was effectively prevented from diffusion by high nitrogen concentrations at the polysilicon/gate oxide interface Without degrading the reliability. In return, increased sheet resistivities and gate depletion have to be taken into account when high nitrogen concentrations are incorporated within the polysilicon gate electrode. (C) 2001 Elsevier Science Ltd. All rights reserved.